NAME

DESCRIPTION

This document describes differences between the 5.13.7 release and the 5.13.8 release.

If you are upgrading from an earlier release such as 5.13.6, first read perl5137delta, which describes differences between 5.13.6 and 5.13.7.

Core Enhancements

-d:-foo calls Devel::foo::unimport

The syntax -d:foo was extended in 5.6.1 to make -d:foo=bar equivalent to -MDevel::foo=bar, which expands internally to use Devel::foo 'bar';. perl now allows prefixing the module name with -, with the same semantics as -M, i.e.

-d:-foo

Equivalent to -M-Devel::foo, expands to no Devel::foo;, calls Devel::foo->unimport() if the method exists.

-d:-foo=bar

Equivalent to -M-Devel::foo=bar, expands to no Devel::foo 'bar';, calls Devel::foo->unimport('bar') if the method exists.

This is particularly useful to suppresses the default actions of a Devel::* module's import method whilst still loading it for debugging.

Full functionality for use feature 'unicode_strings'

This release provides full functionality for use feature 'unicode_strings'. Under its scope, all string operations executed and regular expressions compiled (even if executed outside its scope) have Unicode semantics. See feature.

This feature avoids most forms of the "Unicode Bug" (See "The "Unicode Bug"" in perlunicode for details.) If there is a possibility that your code will process Unicode strings, you are strongly encouraged to use this subpragma to avoid nasty surprises.

The availability of this should strongly affect the whole tone of various documents, such as perlunicode and perluniintro, but this work has not been done yet.

Exception Handling Backcompat Hack

When an exception is thrown in an eval BLOCK, $@ is now set before unwinding, as well as being set after unwinding as the eval block exits. This early setting supports code that has historically treated $@ during unwinding as an indicator of whether the unwinding was due to an exception. These modules had been broken by 5.13.1's change from setting $@ early to setting it late. This double setting arrangement is a stopgap until the reason for unwinding can be made properly introspectable. $@ has never been a reliable indicator of the reason for unwinding.

Stacked labels

Multiple statement labels can now appear before a single statement.

Incompatible Changes

:= is now a syntax error

Previously my $pi := 4; was exactly equivalent to my $pi : = 4;, with the : being treated as the start of an attribute list, ending before the =. The use of := to mean : = was deprecated in 5.12.0, and is now a syntax error. This will allow the future use of := as a new token.

We find no Perl 5 code on CPAN using this construction, outside the core's tests for it, so we believe that this change will have very little impact on real-world codebases.

If it is absolutely necessary to have empty attribute lists (for example, because of a code generator) then avoid the error by adding a space before the =.

Run-time code block in regular expressions

Code blocks in regular expressions ((?{...}) and (??{...})) used not to inherit any pragmata (strict, warnings, etc.) if the regular expression was compiled at run time as happens in cases like these two:

This was a bug, which has now been fixed. But it has the potential to break any code that was relying on this bug.

Deprecations

?PATTERN? is deprecated

?PATTERN? (without the initial m) has been deprecated and now produces a warning. This is to allow future use of ? in new operators. The match-once functionality is still available in the form of m?PATTERN?.

sv_compile_2op() is now deprecated

The sv_compile_2op() API function is now deprecated. Searches suggest that nothing on CPAN is using it, so this should have zero impact.

It attempted to provide an API to compile code down to an optree, but failed to bind correctly to lexicals in the enclosing scope. It's not possible to fix this problem within the constraints of its parameters and return value.

Tie functions on scalars holding typeglobs

Calling a tie function (tie, tied, untie) with a scalar argument acts on a file handle if the scalar happens to hold a typeglob.

This is a long-standing bug that will be removed in Perl 5.16, as there is currently no way to tie the scalar itself when it holds a typeglob, and no way to untie a scalar that has had a typeglob assigned to it.

This bug was fixed in 5.13.7 but, because of the breakage it caused, the fix has been reverted. Now there is a deprecation warning whenever a tie function is used on a handle without an explicit *.

Modules and Pragmata

Updated Modules and Pragmata

Archive::Tar has been upgraded from version 1.72 to 1.74.

Skip extracting pax extended headers.

autodie has been upgraded from version 2.10 to 2.1001.

Test fix in blead for VMS.

B has been upgraded from version 1.26 to 1.27.

Avoid compiler warnings.

B::Concise has been upgraded from version 0.81 to 0.82.

It no longer produces mangled output with the -tree option [perl #80632].

B::Deparse has been upgraded from version 1.01 to 1.02.

Test improvements.

Cwd has been upgraded from version 3.34 to 3.35.

Avoid compiler warnings.

Data::Dumper has been upgraded from version 2.130_01 to 2.130_02.

Avoid compiler warnings.

Devel::Peek has been upgraded from version 1.05 to 1.06.

Avoid compiler warnings.

Test improvements.

Devel::SelfStubber has been upgraded from version 1.03 to 1.05.

Whitespace changes.

Digest::SHA has been upgraded from 5.48 to 5.50.

shasum now more closely mimics sha1sum/md5sum.

Addfile accepts all POSIX filenames.

Dumpvalue has been upgraded from version 1.14 to 1.15.

Test improvements.

DynaLoader has been upgraded from version 1.11 to 1.12.

Remove obsolete RCS keywords.

Env has been upgraded from version 1.01 to 1.02.

Test improvements.

ExtUtils::CBuilder has been upgraded from 0.2703 to 0.280201.

Handle C and C++ compilers separately.

Preserves exit status on VMS.

Test improvements.

ExtUtils::Constant::Utils has been upgraded from 0.02 to 0.03.

Refactoring and fixing of backcompat code, preparing for resynchronisation with CPAN.

A read after a seek beyond the end of the string no longer thinks it has data to read [perl #78716].

Avoid compiler warnings.

PerlIO::via has been upgraded from 0.10 to 0.11.

Avoid compiler warnings.

POSIX has been upgraded from 1.22 to 1.23.

Avoid compiler warnings.

re has been upgraded from 0.14 to 0.15.

Enforce that /d, /u, and /l are mutually exclusive.

SDBM_File has been upgraded from 1.08 to 1.09.

Avoid compiler warnings.

Remove obsolete RCS keywords.

Test improvements.

Socket has been upgraded from 1.91 to 1.92.

It has several new functions for handling IPv6 addresses.

Storable has been upgraded from 2.24 to 2.25.

This adds support for serialising code references that contain UTF-8 strings correctly. The Storable minor version number changed as a result, meaning that Storable users who set $Storable::accept_future_minor to a FALSE value will see errors (see "FORWARD COMPATIBILITY" in Storable for more details).

New Diagnostics

Changes to Existing Diagnostics

The "Found = in conditional" warning that is emitted when a constant is assigned to a variable in a condition is now withheld if the constant is actually a subroutine or one generated by use constant, since the value of the constant may not be known at the time the program is written [perl #77762].

Configuration and Compilation

The Encode module can now (once again) be included in a static Perl build. The special-case handling for this situation got broken in Perl 5.11.0, and has now been repaired.

Testing

Platform Support

Platform-Specific Notes

NetBSD

The NetBSD hints file has been changed to make the system's malloc the default.

Windows

The option to use an externally-supplied crypt(), or to build with no crypt() at all, has been removed. Perl supplies its own crypt() implementation for Windows, and the political situation that required this part of the distribution to sometimes be omitted is long gone.

Internal Changes

The mg_findext() and sv_unmagicext() functions have been added to the API. They allow extension authors to find and remove magic attached to scalars based on both the magic type and the magic virtual table, similar to how sv_magicext() attaches magic of a certain type and with a given virtual table to a scalar. This eliminates the need for extensions to walk the list of MAGIC pointers of an SV to find the magic that belongs to them.

Selected Bug Fixes

BEGIN {require 5.12.0} now behaves as documented, rather than behaving identically to use 5.12.0;. Previously, require in a BEGIN block was erroneously executing the use feature ':5.12.0' and use strict; use warnings; behaviour, which only use was documented to provide [perl #69050].

PerlIO no longer crashes when called recursively, e.g., from a signal handler. Now it just leaks memory [perl #75556].

Defining a constant with the same name as one of perl's special blocks (e.g., INIT) stopped working in 5.12.0, but has now been fixed [perl #78634].

A reference to a literal value used as a hash key ($hash{\"foo"}) used to be stringified, even if the hash was tied [perl #79178].

A closure containing an if statement followed by a constant or variable is no longer treated as a constant [perl #63540].

Calling a closure prototype (what is passed to an attribute handler for a closure) now results in a "Closure prototype called" error message instead of a crash [perl #68560].

A regular expression optimisation would sometimes cause a match with a {n,m} quantifier to fail when it should match [perl #79152].

What has become known as the "Unicode Bug" is mostly resolved in this release. Under use feature 'unicode_strings', the internal storage format of a string no longer affects the external semantics. There are two known exceptions. User-defined case changing functions, which are planned to be deprecated in 5.14, require utf8-encoded strings to function; and the character LATIN SMALL LETTER SHARP S in regular expression case-insensitive matching has a somewhat different set of bugs depending on the internal storage format. Case-insensitive matching of all characters that have multi-character matches, as this one does, is problematical in Perl. [perl #58182].

Mentioning a read-only lexical variable from the enclosing scope in a string eval no longer causes the variable to become writable [perl #19135].

state can now be used with attributes. It used to mean the same thing as my if attributes were present [perl #68658].

Expressions like @$a > 3 no longer cause $a to be mentioned in the "Use of uninitialized value in numeric gt" warning when $a is undefined (since it is not part of the > expression, but the operand of the @) [perl #72090].

require no longer causes caller to return the wrong file name for the scope that called require and other scopes higher up that had the same file name [perl #68712].

The ref types in the typemap for XS bindings now support magical variables [perl #72684].

Reporting Bugs

If you find what you think is a bug, you might check the articles recently posted to the comp.lang.perl.misc newsgroup and the perl bug database at http://rt.perl.org/perlbug/ . There may also be information at http://www.perl.org/ , the Perl Home Page.

If you believe you have an unreported bug, please run the perlbug program included with your release. Be sure to trim your bug down to a tiny but sufficient test case. Your bug report, along with the output of perl -V, will be sent off to perlbug@perl.org to be analysed by the Perl porting team.

If the bug you are reporting has security implications, which make it inappropriate to send to a publicly archived mailing list, then please send it to perl5-security-report@perl.org. This points to a closed subscription unarchived mailing list, which includes all the core committers, who be able to help assess the impact of issues, figure out a resolution, and help co-ordinate the release of patches to mitigate or fix the problem across all platforms on which Perl is supported. Please only use this address for security issues in the Perl core, not for modules independently distributed on CPAN.

SEE ALSO

The Changes file for an explanation of how to view exhaustive details on what changed.

The INSTALL file for how to build Perl.

The README file for general stuff.

The Artistic and Copying files for copyright information.

Module Install Instructions

To install perldelta, simply copy and paste either of the commands in to your terminal